new weil mclain, problem stumped professionals

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Old 11-27-05, 08:47 PM
bunsen
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new weil mclain, problem stumped professionals

Hi folks, Had a new weil mclain (wtgo-3) boiler installed about a month ago. Near the end of its heating cycle a knock or percolating sound comes from the tankless heater behind the limit control. It is fairly loud upstairs and can wake us as it reverberates though the pipes. The installer feels it is overheating/boiling the water there in the coil.We put antisieze on the sensor,tried lowering the temperature range and still the noise. Next a call to my oil company for another troubleshooter. This fellow also thinks its boiling and popping in there also but has no idea why. The system appears to be installed properly. I should add it doesnt seem to do it when calling for hot tap but can be brought on faster when heat and hot tap are used.
Im starting to wonder why I got rid of the 35year old crane.
Thanks for any help on this one.
 
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Old 11-28-05, 06:05 AM
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Hello Bunsen and Welcome to our Do It Yourself Web Site.

Problem stumps the professionals??? HUMMM. Interesting....

A knock or percolating sound is very often caused by excessive sediment and/or rust buildup in the tank and/or lines. FLUSHING often resolves the problem. If the existing tank is not new, flushing is worth a try.

WATER HEATER - STORAGE TANK DRAINING AND FLUSHING INFO:
http://forum.doityourself.com/showthread.php?t=159797

Air bound (air in the lines) is another possible cause.

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Old 11-28-05, 06:46 AM
bunsen
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Thanks for the reply sharp advice. The boiler is new and has done this since new. Air was my first thought also. The system has been bled and still the noise. The sound source is in what I call the coil/Tankless heater behind the limit control. Also it dosent knock everytime usually on the longer cycles. Thanks
 
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Old 11-28-05, 04:16 PM
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Bunsen

This is pretty common on old dry base boilers but on a new wet base???
You might want to contact Weil-McLain or have your installer contact them. With W/M using rubber seals between the sections, I would be afraid to sugget any kind of chemical treatment. When & if you find the cause, please post & let us know in case we happen to run into the same thing.
 
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Old 11-29-05, 04:49 AM
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Hello Bunsen

2 additional possible causes.

Sudden shut down of the circulation pump, after the burners shut down, allows the very hot water to remain within the boilers hot water coils. Which in turn causes excessive expansion of the metal parts caused by the very hot water. A concentration of heat in one localized area. More than the units expansion is designed to handle. Which can cause the knock. Solution is to allow additional time for the pump to remain on after the burners shut down.

A missing and/or defective expansion joint or insulation seal and/or gasket and/or rubber sealer/gasket between the unit and the first pipe out of the boiler and/or anywhere else in the system closest to the boiler.

I am not a boiler service person but do have some contacts in the field. All the above is the info I got from the tech I spoke with. All based upon verbal explaination to me after I explained verbally what the condition was.

Without an onsite visual and physical inspection, difficult to say exactly what is or may be the possible problem and cause. Based up Gradys (Professional Boiler Tech) explaination and all possible causes, there is solution. W/M needs to sendout their factory tech and/or local field tech.

Regards and Good Luck.
 
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Old 11-29-05, 04:00 PM
bunsen
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Thank you for all your replies. This information will be very helpful. I will be sure to keep you posted.
 
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Old 11-29-05, 04:10 PM
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Lightbulb Crazy thought

Just a thought & a question. I am wondering if dissolved gasses are coming out of solution as the water is heated. Do you get spurts of air in the domestic hot water or have you had a problem with air in the heating system?
Something for your installer to try: Remove the domestic coil & install a blank plate. If the noise goes away, it has something to do with the domestic coil. Obviously, this is just for testing purposes since it will leave you without domestic hot water.
 
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Old 11-30-05, 07:24 PM
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Originally Posted by bunsen
Thank you for all your replies. This information will be very helpful. I will be sure to keep you posted.
your hw coil needs to be wired solid had the same thing happen to me you have to take your coil out and wire it so it wont bump against each other
 
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Old 11-30-05, 07:37 PM
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Handyman

The W/M coils don't have any kind of support frame do they? Your idea makes sense. What do you use for wire? I was thinking of about 12ga. solid copper.
 
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